Hello Tight Fart,
I'm keeping my Rib on the Thames this season, mooring it between Putney and Wandsworth bridges.
You will have seen the threads about where to launch, and I also echo the warning about debris. There's quite a bit, so watch out for plastic bags and carry a breadknife in case you pick up a bit of rope. No real problems though, and with no speed limit and being careful of other river users it can be a lot of fun being on the plane through Central London. There is a nice stretch by Battersea Park where you can really open it up, I've done 50 knots there when there's been no other river traffic.
Good places to stop for lunch or drinks are the waiting pontoon at St. Katherines Dock by Tower Bridge, the waiting pier at Chelsea Harbour, Cadagon Pier (for pubs in Chelsea), Putney Pier, The Dove Pier (Hammersmith), Chiswick Pier next to an excellent bar/restaurant called Pissaros, and then there anre numerous places as you dfift on towards Richmond.
I was originally going to take the Rib back to the Solent for the Summer, but I've really enjoyed Thames ribbing, and cruising through the centre of London on a warm summer evening is quite hard to beat.
Have fun, and let me know if you want company.